Case Interview Cheat Sheet: Frameworks, Math Formulas, and Quick Reference (2026)

Seven frameworks, 12 math formulas, and mental math shortcuts fit on one page, but they only matter if you can apply them under pressure. Use this as a quick reference during prep, then immediately test one structure or formula in a timed drill.

The 7 Core Frameworks

Every case can be structured using elements from these frameworks. The key word is "elements": build a custom structure for each case using relevant building blocks, never apply any framework verbatim. McKinsey, BCG, and Bain all penalize framework recitation (Source: IGotAnOffer 2025).

Profitability is the most common type. Equation: Profit = Revenue - Costs. Break revenue into Price x Quantity by segment; costs into Fixed + Variable. Key diagnostic: is this industry-wide or company-specific?

Porter's Five Forces measures industry attractiveness. High supplier/buyer power, substitutes, new entrants, or rivalry reduce profitability.

The 12 Essential Math Formulas

These formulas appear repeatedly across case interviews. You must apply each from memory without a calculator. Every profitability case uses the first three; break-even and contribution margin appear in market entry and pricing cases.

Worked Example: Multiple Formulas Applied

Scenario: A SaaS company charges $200/month per user with 50,000 users. Variable cost: $60/user. Fixed costs: $4.2M/month. They consider a price decrease to $180, estimated to increase users by 20%.

Current state:

• Revenue = $200 x 50,000 = $10M/month
• Profit = $10M - ($60 x 50,000) - $4.2M = $2.8M/month

New scenario:

• Users = 50,000 x 1.20 = 60,000
• Revenue = $180 x 60,000 = $10.8M/month
• Profit = $10.8M - ($60 x 60,000) - $4.2M = $3.0M/month

Verdict: Profit increases $200K/month (+7.1%). The 20% volume increase more than offsets the 10% price reduction. Contribution margin check: extra 10,000 users x $120 = $1.2M exceeds margin loss on existing users of 50,000 x $20 = $1.0M.

Mental Math Shortcuts

No calculators allowed in case interviews. These shortcuts make math fast and reliable under pressure. Practice daily for 2 weeks until each technique is automatic (Source: Hacking the Case Interview 2025).

For the full guide, see mental math for case interviews. To pressure-test these formulas, run a timed math drill.

Case Structure and Synthesis Templates

Structuring a case (first 60-90 seconds): Restate the question and confirm the objective. Identify 3-4 MECE buckets covering key investigation areas. State which bucket to explore first and why. Verify: no overlap between buckets, nothing important missing. See our MECE principle guide.

Synthesis (final 30-60 seconds): "I recommend [action]. Three findings support this: [1], [2], [3]. The main risk is [risk], mitigated by [action]. Next step: [action]." See our synthesis guide.

Common Mistakes to Avoid

Reciting a framework verbatim is penalized at McKinsey, BCG, and Bain; build custom structures using framework elements as building blocks. Jumping to math before understanding the problem wastes time on the wrong question. Calculating silently prevents the interviewer from following your logic and correcting errors.

Forgetting to sanity-check catches errors before the interviewer does: if a coffee shop's annual revenue calculates to $50M, something is wrong. Giving recommendations without data support ("I think they should enter the market") scores poorly.

Related Guides

• Case interview frameworks complete guide: deep dive into all frameworks with examples
• Consulting math formulas: extended formula list with worked examples
• Case interview math practice: timed drills for every formula
• Mental math for case interviews: speed techniques beyond this sheet
• MECE principle explained: the organizing principle behind every framework
• Case interview opening statement: how to present your structure in 90 seconds
• Case interview tips and mistakes: errors that eliminate candidates

About Road to Offer

Road to Offer helps convert this reference into reps. Use structure drills after reviewing frameworks, math drills after reviewing formulas, and a full case when you need to test whether the pieces work together.

• Structure drills: practice building custom issue trees from prompts
• Math drills: test formulas, units, and business interpretation under time pressure
• Full cases: combine structure, math, and synthesis in one scored session

Sources (checked June 17, 2026)

• Hacking the Case Interview frameworks guide: https://www.hackingthecaseinterview.com/pages/case-interview-frameworks
• Hacking the Case Interview cheat sheet and study guide: https://www.hackingthecaseinterview.com/pages/case-interview-cheat-sheet-study-guide
• Hacking the Case Interview 26 essential formulas: https://www.hackingthecaseinterview.com/pages/case-interview-formulas
• Management Consulted case interview formulas: https://managementconsulted.com/case-interview-formulas/
• IGotAnOffer case interview frameworks guide: https://igotanoffer.com/blogs/mckinsey-case-interview-blog/118288068-case-interviews-frameworks-comprehensive-guide
• IGotAnOffer case interview math guide: https://igotanoffer.com/blogs/mckinsey-case-interview-blog/case-interview-maths